Sure, here's an example of a simple mobile backflip game implemented as a single HTML file using JavaScript:
To play the game, you would open the HTML file on your smartphone in a web browser, and then touch the game area to start and stop the backflips. The player (represented by a white square) will perform a backflip every 1.5 seconds while the game is running.
Please note that this is a very basic implementation of a game and can be expanded upon to include more features and better gameplay.